Agaricus bonussquamulosus

Agaricus bonussquamulosus M.Q. He & R.L. Zhao

Fungal Names: FN570359; Faceoffungi Number: FoF 02922

Pileus 55 mm in diam., parabolic when young, then convex; disc slightly depressed; margin straight with appendiculate remains of universal veil; surface dry, completely covered by fine fibrils, and forms fibrillose scales, brown, mess, appressed, denser at disc, scattered towards the margin radially; background white. Context 6 mm thick, flesh, white. Lamellae 6 mm broad, free, crowded, pink, pinkish-brown, brown in age, edge white, even, intercalated with lamellulae. Annulus 8 mm in diam., membranous, single, white, pendant, smooth at both sides. Stipe 70 × 8 (15 at base) mm, white, cylindrical with bulbous base, narrow hollow; surface dry, fibrillose, white. Odour of strongly almonds. Basidiome strongly flavescent when touching, bruising or cutting (especially at the base of the stipe). KOH reaction: positive yellow; Schäffer’s reaction: positive, reddish orange on dry specimen. Basidiospores 5.4–6.4 × 3. 0–4.0 μm, [x = 5.8 ± 0.3 × 3.5 ± 0.2, Q = 1.5–1.8, Qm = 1.7 ± 0.1, n = 20], ellipsoid, elongate, smooth, thick-walled, brown. Basidia 12.1–18 × 5.5–7.5 μm, clavate, hyaline, 4-spored, smooth. Cheilocystidia 13.5–30.5 × 7.6–18 μm, smooth, pyriform most, some broadly clavate, hyaline. Pleurocystidia absent. Pileipellis a cutis composed of hyphae of 4.8–14.0 μm in diam., smooth, cylindrical, hyaline, light yellow, slightly constricted at septa.

Habitat: solitary on soil in forest.

Notes: This new species is characterized by its heavily brown fibrils on the surface of pileus and pyriform cheilocystidia. This new species nests with A. robustulus L.J. Chen, Callac, L.A. Parra, K.D. Hyde & De Kesel, A. fimbrimarginatus L.J. Chen, Callac & K.D. Hyde and A. sp./CA846 under the support of 1.0/88 PP/BS values, and presents as Clade XIV in this study. In the morphology, this new species is different from A. robustulus by its heavily fibrils on the surface of pileus, while those of A. robustulus is forming triangular scales; A. fimbrimarginatus has purplish fibrils on the cap, and those of A. bonussquamulosus is brown colored, also, the relative larger basidiospores of A. fimbrimariginatus (4.7 ± 0.11 × 3.2 ± 0.09) is another difference between these two species.

Fig. 1 Maximum Likelihood (ML) tree of Agaricus section Minores based on LSU, tef1-α, rpb2 and ITS sequences with the outgroup Agaricus campestris. The Bayesian posterior probabilities and bootstrap support values more than 0.9/50% (PP/BS) are indicated at the nodes. The branches in Bold mean the related PP > 0.95. Sequences produced from this study are in blue. “T” refers to sequences from type specimen, and “T” in red refers to the sequences from type specimen and new to science from this study.